Solar Energy Customer Program:
Technical Requirements - Small Systems

The PNM Solar Energy Incentive Program has the following technical requirements for small systems (up to 10 kW):

System type and size

  • System generating electricity using PV or solar thermal technologies with an inverter VAC of 10 kW or less. - For purposes of the technical requirements it is referred to as a "small system".
  • Contact PNM if your small system will have battery or generator backup capability. - The system will require special approval if it will include battery backup or any type of fossil fuel backup generation.

Interconnection

  • Your small system must be designed to connect to the PNM electric grid and - following all inspections and approvals - be interconnected to the grid.
  • The system must interconnect by means of a UL 1741-compliant inverter. - Most 120V and 240V inverters will require a standard 4 terminal (4 jaw) meter base to receive a standard form 1S or 2S meter. - For inverters with different voltage outputs, contact PNM.

Customer disconnect switch

  • PNM requires that a lockable load-break disconnect switch be installed between the output of the inverter and the point of interconnection. - Utility personnel must be able to access the switch. - This switch, referred to as the customer generation AC disconnect switch, must provide a verifiable, visible air gap between the inverter and the point of interconnection. - Be sure to confirm with your installer that opening the customer generation AC disconnect switch will not cause you to be without power from PNM.
  • Circuit breakers and inverter software modes do not meet the disconnect switch requirement.

Required placement of Solar Production Meter

Overview

PNM requires all Solar Production Meters to be within five (5) feet and in line-of-sight from the billing meter. All solar projects must comply with this requirement. Anyone configuring a system outside this required distance must apply for a variance.

By placing the Solar Production Meter and the billing meter together, PNM can ensure the Solar Production Meter is installed in a timely manner and easily read on a regular basis. Keep in mind that both the Solar Production Meter and the billing meter must be accessible by PNM personnel at all times. Please see Rule 13  for information about the Right to Ingress and Egress from any customer premise.

Acceptable Means of Access

Unacceptable Means of Access
  • Homeowner provides gate code or access to a key with installation of a PNM lockbox. Customer is required to update PNM with any code changes.
  • PNM personnel must be accompanied by customer or representative (unless meter is located on a Federal facility).

 

Variance Approval Process

Meter variances will be reviewed on a case-by-case basis by PNM personnel, and approval is at PNM's discretion. In general, variance requests will be granted if any of the following conditions apply to the placement of the production meter:

  • Requires excessive trenching for more than 100 yards
  • Major obstructions interfere with placement
  • Trenching around an excessive amount of concrete is required

Required diagrams and signage

Review the Customer Owned Generating Systems section in the Electric Service Guide for examples of required diagrams.

One-line diagram, site map and safety signage requirements

  • Diagrams and signs must be weatherproof.
  • The one-line diagram should not be placed on the inverter. The inverter could be located on a pole, in the garage or near a ground-mounted system and may be separated from the customer generation AC disconnect and / or REC meter, if present.

Placement of the one-line diagram, site map and safety signage depend on where the REC meter and billing meter (also known as the net meter) are located. See detailed diagrams of the different scenarios (.ppt)

Scenario 1

REC meter and billing meter are grouped together and in plain line of sight.

  • A one-line diagram, or a sketch of the system, is placed at PNM billing meter.
  • A sign must be placed on the customer generation AC disconnect switch, which says: "UTILITY SAFETY DISCONNECT USED TO ISOLATE FROM CUSTOMER GENERATION".

Scenario 2

REC meter and billing meter are installed next to the same building, but not grouped together and not in plain line of sight, or if the PNM billing meter cannot be seen from the customer generation AC disconnect switch.

  • Site map is placed on the PNM billing meter (also known as the net meter).
  • One-line diagram is placed on the REC meter.
  • A sign must be placed on the PNM billing meter which says: "Warning Customer-Owned Generator Connected. See drawing for Disconnect Location".
  • A sign must be placed on the customer generation AC disconnect switch, which says: "UTILITY SAFETY DISCONNECT USED TO ISOLATE FROM CUSTOMER GENERATION".

Scenario 3

REC meter and net meter are installed next to different buildings, are not grouped together and not in plain line of sight. For example, the PNM billing meter is installed next to the house and the REC meter is installed next to a detached garage.

  • Site map is placed on the PNM billing meter (also known as the net meter).
  • One-line diagram is placed on the REC meter.
  • A sign must be placed on the PNM billing meter which says: "Warning Customer-Owned Generator Connected. See drawing for Disconnect Location".
  • A sign must be placed on the customer generation AC disconnect switch, which says: "UTILITY SAFETY DISCONNECT USED TO ISOLATE FROM CUSTOMER GENERATION".

Scenario 4

REC meter and billing meter are grouped together and in plain line of sight, and the system has more than one AC disconnect.

  • One-line diagram is placed at the REC meter.
  • A sign must be placed on the customer generation AC disconnect switch next to the REC meter which says: "UTILITY SAFETY DISCONNECT USED TO ISOLATE FROM CUSTOMER GENERATION".

See three different ways, using a drawing tube, mail slot or permanent label, to permanently store the one-line diagram

REC meter (for REC incentive participants)

  • If you choose to participate in the REC purchase program, your system must have a REC meter.
  • You or your contractor must install the meter base for your system's REC meter; PNM installs the meter.
  • The REC meter must be electrically connected at the output of your PV system inverter before any loads, and must be physically located near your PNM electric billing meter.